Geological or mineral samples have to be reduced to a fine powder for assaying purposes and normally this is carried out in a sample pulverizing machine. Conventional sample pulverizing machines comprise a pair of anvils one of which is rotatable about a horizontal axis and the other being mounted for pivotal movement between co-operating and remote positions with respect to the rotating anvil to permit pulverizing of sample and subsequent access for manual cleaning of the anvils.
Sample grinding times are relatively short, for example up to about thirty seconds. However the subsequent cleaning of the apparatus which is necessary to prevent cross-contamination of samples takes considerable time and thus the full grinding and cleaning cycle averages about three minutes per sample. This is partly due to the configuration of the anvil cavity but mainly it is due to the need to physically open up the apparatus to provide access to the anvils for cleaning.
Many geological samples are very abrasive. Thus the anvils wear quickly and regular adjustment is necessary to compensate for this wear. This can lead to variations in sample particle size if the necessary adjustments are not detected and made. Of course this is undesirable and considerable time is spent checking the wear on conventional pulverizers.